Performance Analysis And Experimental Study Of Two Degree Of Freedom Oscillating Hydrofoil Propulsion

Bionic propulsion as a new propulsion mode is gradually on the rise in recent years. In order to achieve good performance in promoting, bionic propulsion imitates underwater biological ecological structure and motion mode, which provides a new idea for the exploration of underwater propulsion and enriches the underwater propulsion technology.This paper discusses the turtle forelimb hydrofoil propulsion and designs a kind of oscillating hydrofoil propulsion device. The unique turtle hydrofoil motion relying on the coordinated movement can achieve forward motion, sink, yawing, hover and other complex motions.Meanwhile it can also crawl on land achieving amphibious locomotion. This paper mainly discusses the bionic oscillating foil propulsion mechanism analysis, two degree of freedom bionic hydrofoil numerical simulation, the overall design of propulsion device and underwater experiment.Based on the comprehensive researches of the oscillating hydrofoil propulsion methods and the bionic carrier technology of hydrofoil propulsion at home and abroad, hydrofoil propulsion mechanism has been done from the view of lift propulsion mode and resistance propulsion mode. Kinematic model of the hydrofoil coupling motion is established based on the "heave motion" and the "pitch motion". Meanwhile the theoretical analysis including the movement characteristics, coupling analysis of parameters affecting the performance of propulsion is presented and performed, which provides a theoretical basis for the research of propulsion devices.The Fluent software is used to analyze the propulsion performance under different parameter combinations (amplitude of motion, motion frequency, flow velocity, etc.) and the formation and shedding process of the wake vortex is observed. And based on the simulation results, the related driving device parameters are calculated, which lays the foundation for the structure design of the propulsion device.Based on the theoretical analysis and numerical simulation analysis, the related driving devices are selected. The oscillating hydrofoil propulsion device is designed including the drive system design and control system design,which achieves speed closed loop and location closed loop.The experimental platform is built for underwater experiment and a series of experiments are performed under different parameters. In order to analyze the influence of different parameters on the performance of the propulsion, thrust and lift are measured by using a six axis force sensor and related results are compared with numerical simulation results.